Deaths caused by hepatocellular carcinoma account for 600,000 deaths each year and are reportedly ranked the 5th most common cancer-related deaths worldwide (Non Patent Literature 1). Most cases of hepatocellular carcinoma die within 1 year after diagnosis as having the disease. Unfortunately, hepatocellular carcinoma patients are frequently diagnosed at a late stage where the patients rarely respond to therapy capable of curing. Medical procedures including chemotherapy, chemoembolization, cauterization, and proton beam therapy are still insufficiently effective for such patients. Many patients exhibit recurrence of the disease, which proceeds rapidly to an advanced stage with vascular invasion and multisite intrahepatic metastasis, resulting in its 5-year survival rate of only 7% (Non Patent Literature 2). Hepatocellular cancer patients with resectable local tumors have relatively good prognosis, but have a 5-year survival rate remaining at 15% to 39% (Non Patent Literature 3).
Glypican-3 (GPC3) is frequently expressed at a high level in liver cancer. It is therefore considered that GPC3 may be useful for the identification of GPC3 functions in liver cancer or as a target for the treatment of liver cancer or a target of the diagnosis of liver cancer.
GPC3 is known to be expressed on cell surface and then processed at the particular site by convertase, phospholipase D, or Notum (Non Patent Literature 4). A method for selecting an HCC patient by assaying GPC3 present in the plasma of patients is disclosed (Patent Literature 1) as a method based on such an event. A diagnostic product for liver cancer comprising an antibody binding to an epitope in a secreted form of GPC3 secreted into plasma, or a method for diagnosing liver cancer using the antibody has been developed (Patent Literatures 2 and 3). Also, a diagnostic product for liver cancer comprising an antibody binding to an epitope in an anchored form of GPC3 still present on cell surface after processing in a tissue specimen or the like isolated from a patient, or a method for diagnosing liver cancer using the antibody has been developed (Patent Literature 4). A method for selecting a prostate cancer patient by measuring a GPC3 level in blood is disclosed, in addition to liver cancer (Patent Literature 5).
All references cited herein are as given below. The contents described in these literatures are incorporated herein by reference in their entirety. However, this does not mean that any of these literatures are the prior art relative to the present specification.